Homework 09: Chapter 09 Questions

Due: Tuesday, March 27th by 5:59 PM

Header

Please put the following at the top of a flat text file, hwk09.txt:

Homework Questions

Write the answers to the following questions in hwk09.txt:
  1. Consider the following page reference string:
    1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6.
    How many page faults would occur for the following replacement algorithms, assuming one, three, five, or seven frames? Remember all frames are initially empty, so your first unique pages will all cost one fault each. 
    Frames   LRU replacement   FIFO replacement   Optimal replacement
1
3
5
7
  2. Discuss the hardware support required to support demand paging.
  3. Assume we have a demand-paged memory. The page table is held in registers. It takes 8 milliseconds to service a page fault if an empty page is available or the replaced page is not modified, and 20 milliseconds if the replaced page is modified. Memory access time is 100 nanoseconds. Assume that the page to be replaced is modified 70 percent of the time. What is the maximum acceptable page-fault rate for an effective access time of no more than 200 nanoseconds?
  4. The VAX/VMS system uses a FIFO replacement algorithm for resident pages and a free-frame pool of recently used pages. Assume that the free-frame pool is managed using the least recently used replacement policy. Answer the following questions:
    1. If a page fault occurs and if the page does not exist in the free-frame pool, how is free space generated for the newly requested page?
    2. If a page fault occurs and if the page exists in the free-frame pool, how is the resident page set and the free-frame pool managed to make space for the requested page?
    3. What does the system degenerate to if the number of resident pages is set to one?
    4. What does the system degenerate to if the number of pages in the free-frame pool is zero?
  5. Assume that you are monitoring the rate at which the pointer in the clock algorithm (which indicates the candidate page for replacement) moves. What can you say about the system if you notice the following behavior:
    1. pointer is moving fast
    2. pointer is moving slow

Submission

Submit hwk09.txt using the handin program. For example, for this homework, type the following in a terminal exactly as it appears: 
  handin  hwk09  hwk09.txt

Alternatively, you can submit the assignment from any computer via PeerSpace. After successfully logging into PeerSpace, go to Tools, then Assignments. Click on the Submit link.